Openshift/Kuberenets Nodes Ready State

Is there any documentation anywhere within openshift or kubernetes that discusses what kubernetes does to determine that a node is
Ready? I certainly haven’t found any.

The reason why I ask is every once in awhile, I’ll run into an issue where kubernetes is trying to schedule something to a node, that despite being
Ready, there’s something wrong with the node itself. Example today, I’ve got a node that apparently lost his ability to write to any underlying storage mechanism. The
origin-node services sees this in the logs, and this is verified running the
mount command. However, kubernetes doesn’t know anything is wrong, and not a single POD will start up on this node due to this.